Science Trial P2 Marking Schemes

No 1

ANSWER a) The time of a pendulum swing depends on the length of the pendulum. b) constant variable : mass of the pendulum/distance the pendulum is released manipulated variable : length of pendulum swing responding variable : time c) The time of the swing of a simple pendulum depends on the length of the string connected to the pendulum bob used. TOTAL

MARKS 1 1 1 1 1 5

2 a)

rr

Rr r

r

Rr

3

rr

rr

b) 1 : 1 c) The gene of the red flower d) None TOTAL a) 3.0 cm b) 5432-

4

Rr

1

r

R

1 1 1 1 5 1 2

Ticker tape strip

c) Uniform velocity from the first second until the fourth second d) 6 cm TOTAL a) Jar A acts as an control b) Lightly intensity // Temperature c) Q : Magnesium R : nitrate d) To prevent the grow of algae in the culture solution TOTAL

1 1 5 1 1 1+1 1 5

1

No 5

6

7

Answer a) i) refracted ii) white light consists of seven colour components which each colour component has a different velocity when travelling through the prism. b) Red, Orange, Yellow, Green, Blue, Indigo, Violet c) rainbow d) White light TOTAL a) 1. Colouring / sunset yellow 2. Flavouring / vanilla b) 1. colouring – to make food look more attractive 2. flavouring – to make food taste more delicious c) Pandan leaves to give green colouring and sweet aroma to the food TOTAL a) Demodulator b) separates the carrier wave from audio wave c) i) Diode // capacitor

Marks 1 1 2 1 1 6 1 1 1 1 1 1 6 1 1 1 1

//

8

9

d) Modulated wave and carrier wave TOTAL a) i) P : Thermoplastics ii) Q : Thermosets b) P : bottles / containers any other suitable examples Q : Tv casing / pipes any other suitable examples c) Thermoplastic because it can be heated repeatedly (whereas thermosets can only be heated once) TOTAL a) Neutron b) The neutron is absorbed by the uranium nucleus c) The uranium nucleus breaks into two nuclei for example it forms two other atoms d) 1. Barium 2. Krypton TOTAL

2 6 1 1 1 1 1 1 6 1 1 1 1 1+1 6

2

SECTION C QUESTION 10 a) Hypothesis : Steel is more resistance to rust compared to iron. b) Aim of the experiment

1

: To study the resistance of a steel nail and an iron nail to rust

Identification of variables : Manipulated variable : Type of nail Constant variable : Concentration and volume of sodium chloride Solution Responding variable : Rusting of nail Apparatus and materials

: Iron nail, steel nail , two test tubes, sodium chloride solution

Procedure : 1. Each test tube , A and B, are filled with 5 cm3 of sodium chloride solution 2. An iron nail is put into test tube A and a steel nail is put into test tube B. 3. Both test tubes are left on a test tube rack for two days. 4. After two days , the observations are recorded. Tabulation of data Type of nail Iron nail Steel nail

1 ] ]any 2 ] 1 1 1 1 1

: Rusting of nail Iron nail rusts Steel nail does not rusts Total

1 10

3

QUESTION 11 a) Mitosis Two daughter cells are produced The daughter cells have the same genetic information The daughter cells have the same number of chromosomes as the parent cell Crossing-over does not occurs

Meoisis Four daughter cells are produced The daughter cells have different genetic information The daughter cells have half the number of chromosomes of the parent cell Crossing-over occurs [4]

b) Identify the common characteristics : • Two daughter cells are produced or • The daughter cells have the same genetic Information as the parent cell or • The daughter cells have the same number of Chromosomes as the parent cells. [2] Relate the common characteristics in order to construct the initial concept : • The cell division which produces two daughter cells that have the same Genetic information as the parent cell is mitosis.

[1]

Another example : asexual reproduction or any other suitable example Non example : formation of gametes or any other suitable example

[1] [1]

State the actual concept : Mitosis is the cell division which produces two daughter cells that have the same Genetic information as the parent cell. [1]

4

QUESTION 12 a) • Rainforests are producers which help to maintain the amount of carbon dioxide And oxygen in the atmosphere • Rainforests provide habitats for flora and fauna • Rainforests serve as catchments areas • Rainforests regulate the world climate [4] b) • •

•

Identify the problem : How can the extinction of species be prevented? Methods of solving : - Designate forest areas as national parks or forest reserves - Control the logging of timber in natural forests - Replanting of cut timber trees Choose the best method and its explanation : The best method is to establish forest reserves or national parks. This will help endangered species to survive in their natural habitat Without upsetting the ecosystem.

[1]

[3]

[2]

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